Recording and playback apparatus and optical head
US7852734B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 21, 2007 |
| Grant date | Dec 14, 2010 |
| Priority date | — |
| Expiry date | Sep 10, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1381
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The light intensity of a light beam emitted from a light source is appropriately controlled when the light beam is transmitted through a variable optical coupling efficiency device in an optical head. During a read mode, the light beam from the light source is incident on an optical disk at an intensity relatively weaker than that of the light source. By switching the optical coupling efficiency of the variable optical coupling efficiency device between a write mode and a read mode, the light intensity directed to an optical recording medium is substantially varied from the write mode to the read mode. This arrangement eliminates the need for substantially increasing the optical output power ratio of the light source of write power to read power.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.